1. Field of the Invention
The present invention generally relates to Passive Optical Network (PON) communication method and apparatus thereof, more particularly, to PON communication method and system in which a plurality of terminals communicates each other through a parent apparatus, a coupler, and a plurality of child apparatuses.
2. Description of the Related Art
As one of the promising solutions to materialize the fiber-to-the-home concept (FTTH), the passive-optical-network (PON) method that utilizes passive couplers to branch optical fibers at a low cost draws public attention.
Conventionally, ATM-PON in which asynchronous-transfer-mode (ATM) is applied to the PON method has been the main topic of the development. ATM-PON converts information such as Internet Protocol (IP) frames of variable length that is provided by terminals into ATM cells and transfers the ATM cells through the PON.
In the conventional ATM-PON method, however, since asynchronous information of variable length is converted into ATM cells, the overhead portion of the ATM cells is so great compared with the information, that the information is not transferred through PON efficiently.
It is required that the conventional PON be provided with complicated protocols and functions that materialize an ATM layer interface. Additionally, because a child apparatus of the PON to which a user's terminal is connected must have a function of converting IP frames sent by the user's terminal into ATM cells to be transferred through the ATM-PON, the cost of the child apparatus is very high.